Gas heater



Filed Sept. 18, 1967 Fe%. 18, 1969 l. P. s. BAKER ET AL 3,428,040

GAS HEATER Sheet of 2 Feb. 18, 1969 I. P s. BAKER ETAL 3,428,040

- GAS HEATER Filed Sept. 18, 1967 Sheet 2 012 A tlorn e 5 United StatesPatent 3,428,040 GAS HEATER Ian P. S. Baker and Kenneth R. Wade,Liverpool, England, assignors to United Gas Industries Limited, London,England, a British company Filed Sept. 18, 1967, Ser. No. 668,468

U.S. Cl. 126110 Claims Int. Cl. F24h 3/02; F23] 1/00 ABSTRACT OF THEDISCLOSURE The specification describes a balanced flue gas heater, inwhich the flue pipe is coaxially within the air inlet pipe. The airinlet pipe is provided with an annular seal surrounding its outer end oflarger diameter than an exhaust gas deflector assembly on the outer endof the flue pipe. This permits the heater to be installed by simplypassing the balanced flue through a hole in a wall from the interior.

This invention relates to gas heaters.

Various forms of gas heaters have been proposed, in which the air forcombustion of the gas is drawn in from the exterior of a building, at apoint which is closely adjacent the point at which the flue or exhaustgases from the heater are expelled. Such an arrangement is known as abalanced flue. A balanced flue has the advantage that if wind conditionsvary the variation is the same on both the combustion air pressure andon the exhaust gas pressure. Thus the burner of the heater may continueto operate satisfactorily without being affected by fluctuations in theexternal weather conditions.

According to the present invention there is provided a gas heatercomprising a burner mounted in a combustion chamber, a balanced fluecomprising coaxial outer and inner tubes, the inner tube being connectedto the exhaust outlet of the combustion chamber and the annular spacebetween the inner and outer tubes supplying combustion air to theburner, the inner tube extending beyond the outer end of the outer tube,an annular seal surrounding the outer tube, adjacent the outer endthereof, and an exhaust gas deflector at the outer end of the innertube, such deflector being of a transverse dimension less than thetransvers dimension of the annular seal.

With such an arrangement, it is possible to install the balanced fluearrangement of the invention, simply by boring a hole, e.g., by a drill,in an external wall of the building in which the heater is to bemounted. The balanced flue arrangement may then simply be passed throughthe hole in the wall, from the interior. In a convenient construction,the outer tube is in the form of two telescopically arranged tubes, eachprovided with an out- Wardly extending flange, the annular sealincluding at least one resilient ring located between these flanges. Ifone of the outer tubes is mounted on the rear wall of the heater and theother outer tube is mounted on the inner tube by means of spacers, andthe inner tube is adjusted with respect to the rear wall, the twoflanges may compress the annular seal, in an axial direction, thuscausing radial expansion to seal the flue with respect to the wall.

In a preferred construction, the rear of the heater is formed as adouble walled jacket, this jacket being connected to the annular spacebetween the inner and outer tubes, and also being connected to thecombustion chamber, so that air passing through the jacket from theannular space flows to supply combustion air to the burner. Thus acontinuous flow of cool air passes across the rear of the heater,preventing the wall surface to which the heater is attached frombecoming unduly overheated.

The exhaust gas deflector may comprise an outwardly 3,428,040 PatentedFeb. 18, 1969 ICC extending annular flange on the outer end of the innertube, an annular disc mounted co-axially with said inner tube and spacedoutwardly from said annular flange, and a cone, mounted co-axially withsaid inner tube, with its apex towards the tube and spaced from theannular disc. This arrangement provides a particularly simpleconstruction which is eifective in preventing the exhaust gasesemanating from the inner tube from flowing back and into the annularspace and thus to the burner.

Preferably the heater is of the force draught type, in which air isblown by a fan into the combustion chamber.

In order that the invention may more readily be understood, thefollowing descripti-on is given, merely by way of example, referencebeing made to the accompanying drawings, in which:

FIGURE 1 is a schematic sectional side elevation of one embodiment ofgas air heater according to the invention taken along the line I-I ofFIGURE 2; and

FIGURE 2 is a schematic sectional front elevation taken along the lineII-II of FIGURE 1.

This embodiment is a domestic gas-fired convector space heater adaptedto be installed in a room or space on an outside wall thereof. Theheater comprises a sheet metal casing 10 of generally rectangularparallelepipedonal form having a relatively small front to backdimension as compared with its height or side-to-side dimension. In aheater suitable for heating an average sized room or space in a domesticdwelling, a conveniently sized outer casing would be one having aside-to-side width of about 2 feet 6 inches (76.3 cms.), a height ofabout 2 feet (61 cms.) and a front-to-back dimension of about 5 inches(12.7 cms.).

Within the upper part of the outer casing 10, the heater is furnishedwith a sheet metal combustion chamber 11 which is a closed unit, exceptfor an inlet 12 for combustion air and an outlet 13 for combustionproducts. The combustion chamber is extended upwardly at 14, to providea primary heat exchanger, which is connected at its upper part to asecondary heat exchanger 15 which is spaced from and directly behind theprimary hea-t exchanger. The connection between the heat exchanger iseffected by two plunged holes 16, forming ducts therebetween, and theoutlet 13 is formed in the lower part of the secondary heat exchanger.

Extending horizontally within the combustion chamber from side-to-sideof the lower part thereof is a gas burner 17, the supply of gas to suchburner being by way of a pipe 18 passing in a sealed manner through theleft hand side wall (FIGURE 2) of the combustion chamber. A combinedigniter and pilot burner 19, for lighting the burner also passes in asealed manner through the side wall of the combustion chamber, at aposition above the burner 1. A mercury capsule 20 and an auxiliary pilotburner 21 therefor, are positioned below the igniter 19, and act as aflame failure device. The gas pipe 18 and conduits 22, 23 for the saidigniter and flame failure device pass downwardly outside the combustionchamber 10 to controls 24, which may be of a conventional form and whichare mounted in an end portion of the lower part of the casing. Theremainder of said lower part of the casing is mainly taken up by atangential or crossflow blower 25, for speeding up the convection airflow from a convection air inlet 26 to a convection air outlet 27 at thebottom and top of the 'front wall of the casing. When the blower 25 isroted by motor 28, air is blown over and between the primary andsecondary heat exchangers. Adjacent the air inlet 12 of the combustionchamber is mounted a combustion air fan 29, which is of the centrifugaltype, and which is driven by an electric motor 30. The inlet to thecombustion air fan 29 is from the space between the double skins 31, 32of the rear wall of the casing 10, which draws its air from an annularpassage in a combined flue and combustion air inlet assembly, orbalanced flue, positioned at the central region of the rear of the outercasing.

It will be appreciated that the air inlet 12 to the combustion chamberis offset to one side thereof. In order to ensure an even distributionof air to the burner which extends from side-to-side of the combustionspace, a baffle 33 extends horizontally within the combustion spacebelow the burner 17. Baflle 33 extends across the whole front-to-rearwidth of the combustion space and from the side of the combustion spacernearer to the air inlet to a position near, but spaced from the twosides of the combustion space. The baflle has therein a number ofapertures 34 of increasing cross section from right to left, to supplysecondary combustion air at an even rate along the length of the burner17 At its right hand end (FIGURE 1) baflle 33 is bent up to provide anupwardly extending baffle 35 to the left of the inlet aperture 12. Thusair blown into the combustion chamber by fan 29 is divided into twostreams, one flowing under baffle 33, and the other being directed alongthe right hand wall of the combustion chamber to cool it. The airpassing under baflle 33 flows through apertures 34 and also through afurther aperture 36, to provide primary combustion air for burner 16.The remainder of the air under baflle 33 flows upwardly to cool the lefthand wall of the combustion chamber.

The flue outlet from the secondary heat exchanger extends substantiallycentrally of the lower portion of the back wall thereof. Through thisoutlet, passes a flue pipe 37 of the combined flue and combustion airinlet assembly 38, referred to above and to enable this flue pipe tohave sealing press fit in the flue outlet, around the latter, the rearwall of the secondary heat exchanger and the inner skin of the rear wallof the heater are plunged towards one another and clamp between them asealing washer of resilient material adapted to receive the flue pipe37.

The combined flue and combustion air inlet assembly 38 comprises theflue pipe 37 and a pair of telescopically arranged tubes 38, 39surrounding such pipe and defining with the latter an annular space 40through which combust-ion air is drawn into the heater via the spacebetween the two skins of the back wall. The tube 38 having the largerdiameter is, in use of the heater, nearer to the combustion space andhas at its inner end an outwardly projecting flange 41 adapted to abutagainst the wall 42 on which the heater is to be mounted. Such flangecarries a resilient sealing gasket (not shown) against which thesurround of a hole 43 in the outer skin of the rear wall of the heateris adapted to abut when the heater is mounted on the flue and air inletassembly 38. The said flange also has secured thereto a yoke (not shown)through which the flue pipe passes and to which the inner end of thepipe can be secured. The smaller diameter tube 39 fits within the outerend of the larger diameter tube 38 and has intern-ally thereof aplurality of webs or spacers 44 securing the flue pipe centrally Withinsuch tube. Each tube has, at its outer end, an outwardly directed radialflange 45, 46 and between the two flanges are arranged three annularWashers 47 of resilient material, such as polyurethane. At its inner endthe flue pipe has two holes 48 by which the flue pipe can be secured tosaid yoke by a pin (not shown).

The outer end of the flue pipe is provided with an exhaust gas deflectorassembly, comprising a flange 49, a flat annular disc 51 and a conicalmember 52. With this assembly a satisfactory dispersion of the flueor-exhaust gases is effected as they leave the flue pipe. The purpose ofthe outer end assembly of the balanced flue is to eliminate or reducethe drawing of the flue gases back into the annular space 40, and thusinto the combustion chamber, whatever the wind conditions obtainingoutside the wall.

In installing the above described heater, a hole is made, for examplewith a percussion or rotary masonry drill,

in the wall on which the heater is to be mounted, such hole beingslightly larger in diameter than the outer diameter of the radialflanges 45, 46 on the outer ends of the telescopic tubes of the flue andair inlet assembly 38, i.e., about 2 /2 inches (6.05 cms.) diameter. Theexhaust gas deflector assembly 49, 51, 52 is slightly smaller indiameter than the annular washers 47, so that the exhaust gas de flectorassembly may be passed through the hole in the wall from the interior.The balanced flue and exhaust gas deflector is passed through the hole,from inside the room, until the flange 41 on the inner end of the largerdiameter tube engages the inner face of the wall in which the hole hasbeen made. The flue pipe is then pulled inwardly, thereby causing thesmaller diameter tube 39 to which the flue pipe is connected, to betelescoped within the larger tube 38, such action causing the annularwashers 47 to be axially compressed between the flanges 45 and 46 and atthe same time radially expanded into contact with the inner surface ofthe hole in the wall to secure the assembly in the wall. The flue pipeis secured in this position by a rivet, split pin or similar devicebeing passed through the holes in the yoke (not shown) and appropriatelydrilled holes 48 in the inner end of the flue pipe, the inner end of thepipe being cut to length as required. The heater is then fixed inposition over the protruding end of the flue pipe thus passing sealinglyinto the outlet 13 of the secondary heat exchanger, and the annularspace around the flue pipe being put into communication with the spacebetween the two skins of the rear wall of the heater.

The heater may be thermostatically controlled individually or incombination with a group of heaters in different parts of a house orother structure.

In the embodiment specifically described, the lanced flue assemblyprojects from the back of the heater and the latter is designed formounting in a room or space on an outside wall thereof. In amodification, the combined flue and air inlet assembly is designed toproject from the side of the heater so that the latter may even bemounted on an internal wall, the said assembly being led to the outsidein any appropriate manner. In the latter arrangement, the flue outletfrom the secondary heat exchanger will be arranged in the side facethereof.

If desired, the flat annular disc 51 may be omitted from the deflectorassembly. This, however, reduces the efficiency of the assembly.

We claim:

1. A gas heater comprising in combination:

(a) a combustion chamber;

(b) a burner within said combustion chamber;

(c) an exhaust gas outlet means for said combustion chamber;

(d) coaxial inner and outer tubes defining therebetween an annularspace;

(e) said inner tube connected to said exhaust gas outlet means and saidannular space connected to said combustion chamber adjacent said burnereffective to supply combustion air to said burner;

(f) an outer end to each of said inner and outer tubes, said inner tubeextending axially beyond said outer tube;

(g) an annular resilient seal surrounding said outer tube adjacent saidouter end; and

(h) exhaust gas deflector means at the outer end of said inner tube andof a transverse dimension less than the transverse dimension of saidannular seal.

2. A gas heater as defined in claim 1 wherein said outer tube is in theform of two telescopically arranged tubes, wherein each of saidtelescopically arranged tubes is provided with an outwardly extendingflange and wherein the annular resilient seal is located between saidoutwardly extending flanges.

3. A gas heater as defined in claim 2, wherein the heater is providedwith a rear wall, and one of said outer tubes is mounted on said rearwall, wherein spacers mount the other of said outer tube on the innertube and wherein said inner tube is axially adjustable relative to saidrear wall.

4. A gas heater as defined in claim 3, wherein the heater is providedwith an inner rear wall spaced inwardly from said rear wall and definingtherewith a jacket extending across the rear of the heater, a connectionbetween said jacket and said combustion chamber and said annular spacebetween said inner and outer tubes opening into said jacket.

5. A gas heater as defined in claim 1, wherein said exhaust gasdeflector means comprises an outwardly extending annular flange on saidouter end of said inner tube, an annular disc mounted coaxially withsaid inner tube and spaced outwardly from said annular flange, and anoutwardly divergent cone, mounted coaxially with said inner tube andspaced outwardly from said annular disc.

6. A gas heater as defined in claim 1, wherein said heater comprises afirst portion extending upwardly above said burner and a second portionextending adjacent said first portion, an upper part to said first andsecond portions and a lower part to said second portion, a connectionbetween said upper parts of said first and second portion, said exhaustgas outlet means including an outlet in the lower part of said secondportion.

7. A gas heater as defined in claim 6, wherein said first and secondportions define therebetween a gap, said heater further comprising across flow blower eflective to blow air between said first and secondportions, through said gap.

8. A gas heater as defined in claim 1, wherein said burner extendslaterally across said heater, and a fan is connected to said inner tubeand to said combustion chamber effective to direct combustion airlaterally across said combustion chamber towards said burner.

9. A gas heater as defined in claim 8, wherein an upwardly extendingbaflle is mounted in said combustion chamber between said fan and saidburner elfective to divide the fiow of air first downwardly to saidburner and second upwardly into said combustion chamber.

10. A gas heater as defined in claim 9, wherein a horizontal bafile ismounted beneath said burner, and apertures are defined in saidhorizontal baflle.

References Cited UNITED STATES PATENTS 2,632,435 3/1953 Lundstrum 126-853,056,397 10/1962 Little 12685 3,263,749 8/1966 Dormitzer 126-110 JAMESW. WESTHAVER, Primary Examiner.

US. Cl. X.R

